Q&A Forum
Hello
I have been building a hydraulic load cell to dyno my turbocharged mach z 1000 twin snowmobile. I had a longer drive axle shaft made and removed the track and suspention to allow the shaft to go straight thru bulk head and connect to hydraulic pump. The motor should make about 300 to 400 hp at 25 lbs of boost. The axle will be after clutch and gearing which will be reduce to 2 to 1 ratio because motor spins 8000 rpms so at the pump it should be 4000 rpms after the gear reduction. Would the torque reading be double then what it actual is because of ratio change. Would your software work on this system and what size pump would I need.
Hi,
Sounds like a badass snowmobile!!
Yes, the torque will double when the RPM is reduced by 2. Horsepower will read the same no matter where you measure it. The software supports gearing and automatically calculates the torque in the engine. You can enter the gear ratio in the options.
300-400 HP is very high for a hydraulic pump brake. You will need a very high flowing pump (in the order of 200-300 ml/rev). You can find vane pumps that can do this, but they also need very high RPM and high pressure rating... And you need a hose and restrictor valve that are able to cope. There is a calculator here if you want to pursue this: http://yourdyno.com/choosing-the-right-hydraulic-pump/, but make sure to double and triple check all specs so the design is safe.
A better solution may be a water brake (expensive unfortunately) or see if you can find an old Eddy current brake from a bus or truck.
Cheers,
Jostein
Going to go stick with a hydraulic pump, I have built my system around this theory and would like to make it work.